A few months ago, after discarding some store bought purple potatoes that had gone old, I managed to grow some nice potato plants. Recently, however, I have been noticing purple blotches on the leaves which seems abnormal since with my previous harvests and other reference plants, they don’t seem to have it. The spots have been sparse and only on a few leaves
I haven’t been able to find much on the internet. is it likely early blight? If so, what is to be done?
Looking at the images, those purple-black spots on the potato leaves appear to be symptoms of Early Blight (Alternaria solani), a common fungal disease that affects potato plants. The spots have characteristic dark, irregular lesions scattered across the leaf surface. Older leaves are affected first, and the spots expand over time.
Remove infected leaves and water at the base of the plant (don't wet leaves), improve air circulation by spacing the plants properly, and use a fungicide. Here are some recommendations for fungicides:
Tip: To prevent resistance, alternate between fungicides with different modes of action (e.g., combine contact fungicides like mancozeb with systemic ones like thiophanate-methyl or azoxystrobin).
Magnesium-deficiency can look like that on tomatoes. Potatoes are related. I'm not sure if that's the problem, but you never know.
